Gardening Articles: Care :: Seeds & Propagation

The Other Pollinators (page 3 of 6)

by Amy Bartlett Wright

Bumblebee (Bombus)

This medium- to large-sized insect is covered with black and yellow or orange hairs. Like honeybees, they're social insects with a queen that rules a colony. In the spring, the queen selects a nest site in the ground for a colony of 100 to 200 bees. The site may be an abandoned rodent burrow or a formerly occupied bumblebee nest. The queen first raises workers who tend the hive and colony. They forage, collect and store nectar, and care for the young. Late in the season, males mate with females who will be the next year's queens. Bumblebees are abundant on late-flowering ornamentals. Fall cold kills all members except the new queens.

Bumblebees have long proboscises (tongues) that enable them to reach nectar in flowers with deep nectaries (plant glands that secrete nectar). Plants such as tomatoes have pollen hidden inside anthers that are like saltshakers, making pollen collection difficult or impossible for most bees. The bumblebee has a specialized technique to actively collect such pollen: It tucks its abdomen under and shakes the pollen out of the flower and onto its body hairs.

Bumblebees are widespread, common, and polylectic pollinators (they will visit many types of flowers). Bombus grisiocolus and B. occidentalis are found throughout the continental United States. Bombus impatiens is small and common in eastern states, as is B. ternarius. If you want to attract many species of bumblebees to your garden, leave a clay pot with a hole in the bottom upside down in a garden bed in the spring.

Squash Bee (Peponapis pruinosa)

These native wild bees are solitary: They live on their own without a colony, and females lay single eggs in protective cells. Squash bees are specialized: they collect pollen and nectar only from the flowers of cucurbits (squashes, pumpkins, and gourds). In the late 1970s, Vincent Tepedino, research entomologist at the USDA Agricultural Research Station Bee Biology Laboratory at Utah State University, compared the squash bee's pollination skills with those of the honeybee and found the wild bee to be more efficient, considering frequency of visits and amount of pollen deposited on the flower. Squash bees are up at dawn, well before honeybees are active, so they can reach squash flowers early in the morning. Other scientists have observed the squash bee in a wide range of activities within the flower: resting, grooming, and mating in the flower structure, in addition to feeding on nectar and pollen. All that activity means more pollen collecting but only for a life span of about 2 months, until the food source is gone. Squash bees are found in most regions of the United States, but not in the Northwest.